This was a tribe of people that lived in Arabia Petraea, between the Dead Sea and the Red Sea. They were not the descendants of Amalek, the son of Eliphaz, for they existed in the days of Abraham (Genesis 14:7). They were probably a tribe that migrated from the shores of the Persian Gulf and settled in Arabia.
They were apparently a pastoral, and therefore probably a nomadic people. Their kings bore the hereditary name of Agag (Numbers 24:7; 1 Samuel 15:8). They attempted to stop the Israelites when they marched through their territory (Deuteronomy 25:18), attacking them at Rephidim (Exodus 17:8-13; compare Deuteronomy 25:17; 1 Samuel 15:2).
We read of them subsequently as being in league with the Moabites (Judges 3:13) and the Midianites (Judges 6:3). Saul finally desolated their territory and destroyed their power (1 Samuel 14:48; 15:3), and David recovered booty from them (1 Samuel 30:18-20).